Symeon 15 was a basilikos protospatharios and o... (?ostiarios); owner of a seal dateable to the eighth or ninth century: Konstantopoulos, JIAN 7, 513. The name and titles read: [Σ]υμεὼν βασιλικῷ πρωτοσπ[α]θ[α]ρήῳ ο.... The last letter presumably is the first letter of his post, perhaps ostiarios although evidence is lacking that this post was combined with the dignity of basilikos protospatharios.

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